1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY COMPONENTS --
5 -- S Y S T E M . C O M P A R E _ A R R A Y _ U N S I G N E D _ 1 6 --
9 -- Copyright (C) 2002-2023, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with System
.Address_Operations
; use System
.Address_Operations
;
33 with System
.Storage_Elements
; use System
.Storage_Elements
;
35 with Ada
.Unchecked_Conversion
;
37 package body System
.Compare_Array_Unsigned_16
is
39 type Word
is mod 2 ** 32;
40 -- Used to process operands by words
42 type Half
is mod 2 ** 16;
44 -- Used to process operands by half words
46 type Uhalf
is new Half
;
47 for Uhalf
'Alignment use 1;
48 -- Used to process operands when unaligned
50 type WP
is access Word
;
51 type HP
is access Half
;
52 type UP
is access Uhalf
;
54 function W
is new Ada
.Unchecked_Conversion
(Address
, WP
);
55 function H
is new Ada
.Unchecked_Conversion
(Address
, HP
);
56 function U
is new Ada
.Unchecked_Conversion
(Address
, UP
);
58 -----------------------
59 -- Compare_Array_U16 --
60 -----------------------
62 pragma Annotate
(Gnatcheck
, Exempt_On
, "Improper_Returns",
63 "early returns for performance");
65 function Compare_Array_U16
66 (Left
: System
.Address
;
67 Right
: System
.Address
;
69 Right_Len
: Natural) return Integer
71 Clen
: Natural := Natural'Min (Left_Len
, Right_Len
);
72 -- Number of elements left to compare
76 -- Pointers to next elements to compare
79 -- Go by words if possible
81 if ModA
(OrA
(Left
, Right
), 4) = 0 then
83 and then W
(L
).all = W
(R
).all
86 L
:= L
+ Storage_Offset
(4);
87 R
:= R
+ Storage_Offset
(4);
91 -- Case of going by aligned half words
93 if ModA
(OrA
(Left
, Right
), 2) = 0 then
95 if H
(L
).all /= H
(R
).all then
96 if H
(L
).all > H
(R
).all then
104 L
:= L
+ Storage_Offset
(2);
105 R
:= R
+ Storage_Offset
(2);
108 -- Case of going by unaligned half words
112 if U
(L
).all /= U
(R
).all then
113 if U
(L
).all > U
(R
).all then
121 L
:= L
+ Storage_Offset
(2);
122 R
:= R
+ Storage_Offset
(2);
126 -- Here if common section equal, result decided by lengths
128 if Left_Len
= Right_Len
then
130 elsif Left_Len
> Right_Len
then
135 end Compare_Array_U16
;
137 pragma Annotate
(Gnatcheck
, Exempt_Off
, "Improper_Returns");
138 end System
.Compare_Array_Unsigned_16
;